I Am Number Four (PG-13) will be lucky to reach that spot on the box office chart this weekend, regardless of how many young adult readers bought Pittacus Lore's book. This isn't Twilight, you know. More like that Percy Jackson and the Olympians flick that seemed like a good idea at the time for gravy-train jumping.

Alex Pettyfer, breathlessly hyped as the next Robert Pattinson, stars as John Smith, a regular new kid in a small Ohio town. Except he isn't a normal teenager; he's a Loric alien on the run from the evil Mogadorians trying to kill him and eight other refugees. John is No. 4 on the hit list. It could be worse. He could be No. 9 and the movie would be twice as long with backstory.

I Am Number Four co-stars Pettyfer's girlfriend, Dianna Agron — who must receive less fan mail than her Glee cast mates — and Timothy Olyphant, who must have taken the gig before Justified made him a hot commodity. No surprise: The movie wasn't screened for Weekend review.

Liam Neeson is nicely settling into roles that Harrison Ford played so well a couple of decades ago: the uptight, upright citizen thrust into a perplexing situation that could kill him. Taken turned out to be a crackling thriller and box office hit in 2008; Unknown (PG-13) looks like more of the same good thing. Neeson plays Dr. Martin Harris, who awakens from a coma to find that his identity has been hijacked by someone (Aidan Quinn), and the scheme may include his wife (January Jones, TV's Mad Men). The only person believing his claim is the cab driver (Diane Kruger, Inglourious Basterds) whose traffic accident caused his injury. Frank Langella is lurking in the shadows, which is never a good sign in mysterious situations like this. Unknown wasn't screened in time for Weekend. Find a review at tampabay.com/features, or Friday on Etc, Page 2B.

What can be less promising than a third movie starring Martin Lawrence in drag? Big Mommas: Like Father, Like Son (PG-13) lowers the anticipation bar with two — count 'em, two — actors cross-dressing in extremely unconvincing fashion, surrounded by lunkheads believing them. Times have been tough for Lawrence, but this is desperate.

He returns as Malcolm, the bumbling FBI agent solving cases against all odds. This one involves his son Trent (Brandon T. Jackson), who witnessed a murder, and the killer knows it. The only solution, of course, is to pull out the Big Momma wig, fat suit and muumuu, dress Trent like a woman and go undercover in an all-girls school.